For a number of known reasons, bone fixation devices are useful for promoting proper healing of injured or damaged vertebral bone segments caused by trauma, tumor growth, or degenerative disc disease. The fixation devices immobilize the injured bone segments to ensure the proper growth of new osseous tissue between the damaged segments. These types of bone fixation devices often include internal bracing and instrumentation to stabilize the spinal column to facilitate the efficient healing of the damaged area without deformity or instability, while minimizing any immobilization and post-operative care of the patient.
One such device is an osteosynthesis plate, more commonly referred to as a bone fixation plate, that can be used to immobilize adjacent skeletal parts such as bones. Typically, the fixation plate is a rigid metal or polymeric plate positioned to span bones or bone segments that require immobilization with respect to one another. The plate is fastened to the respective bones, usually with bone screws, so that the plate remains in contact with the bones and fixes them in a desired position. Bone plates can be useful in providing the mechanical support necessary to keep vertebral bodies in proper position and bridge a weakened or diseased area such as when a disc, vertebral body or fragment has been removed.
Such plates have been used to immobilize a variety of bones, including vertebral bodies of the spine. These bone plate systems usually include a rigid bone plate having a plurality of screw openings. The bone plate is placed against the damaged vertebral bodies and bone screws are used to secure the bone plate to the spine, usually with the bone screws being driven into the vertebral bodies.
Bone screws can be supported in a spinal plate in either a rigid or a semi-rigid fashion. In a rigid fashion, the bone screws are not permitted to move angularly relative to the plate. Conversely, in a semi-rigid fashion, the bone screws can move relative to the plate. The use of rigid and semi-rigid bone screws allow the surgeon to select the appropriate bone screw based on the particular treatment. While current plating systems can be effective, they typically require the use of different plates to obtain the desired bone screw fixation.
Accordingly, there remains a need for an improved plating system that allows the surgeon to use a single plate and to select between various types of bone screw fixation.